extend Boolean
    method and: other::Boolean
        self
           ifTrue: { other }
           ifFalse: { False }

    method and: other1 and: other2
        self
           ifTrue: { other1 and: other2 }
           ifFalse: { False }

    method and: other1 and: other2 and: other3
        self
           ifTrue: { other1 and: other2 and: other3 }
           ifFalse: { False }

    method or: other::Boolean
        self
           ifTrue: { True }
           ifFalse: { other }

    method not
        self
           ifTrue: { False }
           ifFalse: { True }

    method ifTrue: block
        self
           ifTrue: block
           ifFalse: { False }

    method ifFalse: block
        self
           -- FIXME: returning True in the first leg seems strange, but breaks a couple
           -- of tests. Should either explain the rational or return False.
           ifTrue: { True }
           ifFalse: block

    method toString
        self
           ifTrue: { "True" }
           ifFalse: { "False" }
end